host.rb

class Host < ActiveRecord::Base
  attr_accessible :delay, :error, :host, :port, :status
  has_many :checks
  has_many :relations
  has_many :users, through: :relations
end

relation.rb

class Relation < ActiveRecord::Base
  attr_accessible :host_id, :user_id
  belongs_to :host
  belongs_to :user
end

user.rb

class User < ActiveRecord::Base
  devise :database_authenticatable, :registerable, :recoverable, :rememberable, :trackable, :validatable
  attr_accessible :email, :password, :password_confirmation, :remember_me

  has_many :relations
  has_many :hosts, through: :relations
  has_one :phone
  
  def host 
    Hosts.where(:user_id, id)
  end
  
end